U.S. officials said the administration faced little choice other than to step up its support or risk watching as rebels lose still more ground to a resurgent Assad regime backed by Russia, Iran and soldiers from the militant Hezbollah group.

That makes sense. The U.S. doesn’t like Hezbollah or Iran, and it certainly doesn’t want the Assad regime to win the war. Washington’s also not crazy about Russia’s foreign policy in the Middle East. But the administration is not going to give the rebels enough to do much more than keep fighting. Reports the New York Times:

The officials held out the possibility that the assistance, coordinated by the Central Intelligence Agency, could include antitank weapons, but they said that for now supplying the antiaircraft weapons that rebel commanders have said they sorely need is not under consideration.

That makes sense too. Obama may want to keep the opposition alive, but it would be dangerous to give them weapons that could be used to take down passenger planes since the rebels are deeply intertwined with jihadist factions, including one, Jabhat al-Nusra, the administration listed as an al Qaeda ally last December.

The administration declared it was taking this latest Syrian half-step because America’s spies had concluded that Assad had used chemical weapons. “The intelligence community estimates that 100 to 150 people have died from detected chemical weapons attacks in Syria to date,” deputy National Security Advisor Ben Rhodes told reporters Thursday. Said Rhodes, Obama “has said that the use of chemical weapons would change his calculus, and it has.”

But there could be another reason for doing just enough to keep the two sides fighting. The Assad regime is increasingly relying on Hezbollah to fight throughout the country. The rebels for their part are relying on jihadist and al Qaeda allies to fight back. Keeping two of the United States’ most active terrorist enemies fighting each other might be seen in some circles as not such a bad thing.

Such a realpolitik approach could carry dangers, though. Advocates of robust intervention, like John McCain and Lindsey Graham, have said that allowing the war to continue could dangerously threaten U.S. interests by spilling over into neighboring allied countries, like Jordan and Turkey. “This is a regional conflict,” McCain said Thursday, “Jordan is destabilized. Lebanon is about to erupt into sectarian violence. Jihadists are flowing in from all over the Middle East. This is erupting into a regional conflict where the United States’ vital national security interests are at stake.” McCain advocates establishing a no-fly zone.

Allowing the bloodshed to continue also would cut against the declared policy of the administration and the humanitarian leanings of Obama’s incoming National Security Advisor, Susan Rice, and his nominee to be U.N. Ambassador, Samantha Power. In theory, they all want to diminish civilian deaths and end the war diplomatically. “The United States is providing $515 million in humanitarian assistance for the Syrian crisis and seeking to rally others to provide more as well,” Rhodes said Thursday.

Perhaps the U.S. will prevent further civilian deaths and hasten the war’s end by declaring it is acting in response to the use of chemical weapons and by taking limited measures to counter Assad’s progress. But sometimes to see the true goals of a country’s diplomacy, it’s best to look at the effects of what its leaders do rather than the things they say.